This invention relates to bird repelling systems and, more particularly, to such systems particularly suited for vineyards.
Birds are a significant threat to vineyards. For example, a single flock of birds could spoil ten tons of fruit in a few days. Accordingly, many methods and systems have been designed to protect vineyards from the ravages of birds.
One method of protection, which is extremely effective, involves netting which is placed over the vines. The birds do not eat the fruit through the netting. A major drawback of netting, however, is the time it involves. It not only takes a great deal of time and manpower to cover the vineyard with netting, it also takes as much or more time to remove the netting when it is time to pick the grapes. Moreover, if left in place for any length of time, weeds grow up through the netting and the grape vines grow through it as well. This makes it doubly difficult to remove the netting when necessary. When removed, the netting often brings along trash and has many tears, both of which reduce the reusability of the netting.
There have been chemical sprays used in the past which repelled the birds, but with increasing concern about the use of chemicals on food products these sprays have become unacceptable. Another spray, made of natural ingredients such as garlic and red pepper, is still used, particularly for table grapes. But it also has drawbacks. When it rains, this mixture forms a residue on the grapes. Such a mixture is especially undesirable for wine grapes since it can result in getting garlic and red pepper in the wine.
There are more direct approaches taken to repelling birds from vineyards. Some vineyard owners have been known to shoot birds with shotguns, but this method is relatively inefficient and the effect of an assault on the birds is relatively short-lived.
Some other bird repelling systems involve various kinds of scarecrows or sound generating systems. For example, one such system generates screeches similar to those of birds in trouble. Such systems increase the anxiety level of the birds eating grapes in the vineyard, but do little to drive them off.
There have been general attempts to repel birds by using electrical shocks. Such systems are shown in U.S. Pat. Nos. 3,366,854 to Robinson, 4,015,176 to Shanahan et al., and 4,299,048 to Bayes.
In the Robinson patent, the bird repelling system is in the form of a cable with an insulative body separating two conductors. The conductors are generally held within the cable, but part of their surfaces are exposed so that when a bird lands on the cable it completes a circuit between the two conductors, receives a shock, and leaves. This system apparently teaches placing this two-conductor cable everywhere it is desired to repel the birds. Thus, for a relatively large area, a large amount of relatively expensive cable would be required. To improve its operation, the system of Robinson optionally includes the use of support posts (FIG. 5) to raise the two-conductor cable above the surface such as a ledge on which it would otherwise lie.
The Shanahan et al system is a general purpose bird repelling system for use in fruit orchards, vineyards, and window ledges. Shanahan teaches that when an outdoor area is to be protected, the arrangement shown in FIG. 4 thereof is to be used. Upright posts 41 are secured in the ground, and a perch or cable 42 is strung between the posts. The cable is a flexible cord of insulative material carrying two electric wires. The wires are charged from a battery 43. When birds alight on the cable, they receive a shock strong enough to chase them away, but not necessarily strong enough to stun them. The height of the posts may vary from a few inches to many feet, depending upon the height of the plants being protected.
The Bayes system involves a similar electrified cable with two conductors, one on each side. When enough birds land on the cable to make it worthwhile, they are all electrocuted at once.
All these electrical systems require an extensive amount of cable, the cable is not a standard item and hence is relatively expensive, and separate means for suspending the cable is required or suggested.